Lubricating composition



Patented May 1 1, 1943 2,318,630 I LUBRICATING COMPOSITION Carl F.Prutton, Cleveland, Ohio, assignorto The Lubri-Zol Cotporation,Wickliffe, Ohio, a. corporation of Ohio No Drawing. Application Augusts, 1938,

Serial No. 223,694

5 Claims.

The present invention relates as indicated to lubrication and moreparticularly to methods of lubricating and lubricating compositionscharacterized by their ability to withstand extreme unit pressuresbetween the'bearing surfaces which the same are called upon tolubricate, without the disadvantages of instability and gum-formingtendencies which characterize many similar lubricating compositions nowcommonly available.

This application is a continuation in part of my copending applicationsSerial No. 7373070. filed July 26, 1934, and Serial No. 193,960, filedMarch 4, 1938.

It is a principal object of this invention to provide a lubricatingcomposition utilizing certain compounds of sulphur as the means forproviding the improved type of lubrication above identified, suchcompounds being used either in their pure state or admixed withlubricating compositions such as mineral oils and the like.

By extreme pressures, as referred to above, is meant pressures of or inexcess of 10,000 pounds per square inch, such pressures now being con1--monly encountered in hypoid gears, bearings, contact surfaces ofcylinders and piston rings in internal combustion engines, and manyother points. Such pressures tend to cause the rupture of the continuousthick film of lubricant which separates bearing surfaces under moremoderate conditions. A region of thin film lubrication results which isalso sometimes described as boundary lubrication.

It is therefore an object of my invention to provide a lubricatingcomposition and method of lubricating which will afiord efiicientlubrication and protection to the relatively moving metallic surfacesunder conditions of extreme pressure,

bricating oil it is obvious that generally only such amounts of theaddition agent may be included as are soluble in the specified 'amo ntof oil. By the term soluble as herein used it is intended to indicatethe ability to form not only true solutions but also any form ofsubstantially permanently homogeneous composition when,

incorporated in mineral oil. With most of the compounds there is usuallylittle difficulty, especially if the incorporation is effected in themanner described in Cornell Patent No. 2,042,880, and since relativelysmall proportions usually give improved results it is seldom ofimportance that the addition agents be oil-soluble in all proportions.Also, certain compounds are of value as gelling or bodying agents whenused in amounts greater than are strictly soluble.

While for certain specialized uses the mom,- and di-sulphides may beemployed as the sole lubricant this invention contemplates that ingeneral they will be employed as addition agents either the soleaddition agent or in combination with others) to mineral lubricatingoils in amounts ranging from about .2% to about by weight, based'on theamount of mineral oil. From about V2% to 7%, or preferably from about 1%to about 5% will be found to be a de- Sir able proportion for generaluse although larger Other objects of this invention will appear as thedescription proceeds.

To the accomplishment of the foregoing. and related ends, saidinvention, then, consists of the means hereinafter fully described andparticularly pointed out in the claims, the following descriptionsetting forth in detail certain approvedcombinations -of ingredientsembodying my invention, such disclosed means constituting, however, butcertain of various forms in which the principle of the invention may beused.

Briefly stated, my invention comprises the discovery that a certainclass of sulphur compounds, namely the organic monoand di-sulphides,although stable and relatively chemically inactive at ordinarytemperatures and pressures, will, nevertheless, when present in alubricant film and subjected to the conditions imposed on the bear- Whenused in conjunction with a mineral luamounts up to about 10% or more.may be found more advantageous for certain uses. The proportion added,however, is often limited by the limit of solubility in the particularoil. The final products should contain an amount of the addition agentsufiicient to increase the film strength of the lubricant, to asubstantial degree. The required minimum amount will usually be found tobe about 0.2%, in order that the lubricant may exhibit sufficientextreme pressure properties to be commercially feasible.

Although the oil base is referred to above as a mineral lubricating oilit is to be understood that any other suitable hydrocarbon lubricatingoil, whether naturally occurring orsynthetic may be employed as the oilbase. For most purposes mineral lubricating oils having a viscosity fromabout 50.to 250 second Saybolt at 210 F. are

entirely suitable, and for certain purposes, as for example'gearlubrication, a viscosity range of to 200 seconds is desirable. v

It' is aso within thev contemplation of this invention to provide theaddition agent in the form of a concentrate in a suitable ,oil, said oilcontaining rather high percentagesof the addition agent. Suchconcentrates are employed for future blending with a lubricating oil inthe proportions desired for the particular conditions of use.

When still greater resistance to extreme pressure conditions isdesiredthan that afforded by the addition agent ofth is i nve tio l t va 2 often be found advantageous to employ a small amount of a separateorganic halogen compound in the lubricant which will cooperate with theaddition agent of this invention to increase the film strength (e. g. asindicated on the Almen Machine) to a degree greater than the sum ofObviously the addtion agent chosen should be sufficiently oil-soluble sothat the amount used the effects of either addition agent when employedalone. I Since, in general, the loss of the addition agent byvolatilization will be less for compoundshaving a low volatility, thevapor pressure of the Coastal oils and lower for the viscousPennsylcompounds should, for most purposes, be less.

than atmospheric pressure at temperatures up to 140 C. It is usuallydesirable, especially for use in internal combustion engines, that thevapor pressure be less than atmospheric at temperatures up to 170 C. Inthe case of compounds which are stable at temperatures up to theirboiling-points, this condition may be expressed by stating that theboiling point of the compound should, in general, be higher than 140 C.,and for certain uses, such as in internal combustion engines, higherthan 70 C.

' Examples of the types of compounds which may be employed in accordancewith my invention are the di-aryl and di-alkyl sulphides anddi-sul-phides and also sulphides and di-sulphides containing both analkyl and an aryl radicle, e. g.:

-Di'-alkyl sulphides, e. g.:

'Di-amyl sulphide Di-lauryl sulphide Arylated alkyl sulphides, e. g.:

Dibenzyl sulphide Di-aryl sulphides, e. g.-: Di-phenyl sulphide ni alkyldisulphides, e. g.:-

Di-ethyl disulphide Di-n-butyl disulphide Di-amyl disulphide Arylatedalkyl disulphides, e. g.:

Di-benzyl disulphide Di-phenyl di-ethyl disulphide (CeHs-C2H4-S)2Di-methyl di-benzyl disulphide (CH3CsH4-CH2-S) a Di-aryl disulphides, e.g.: Di-phenyl disulphide Alkylated aryl disulphides, e. g.:

Di-tolyl disulphide Di-xylyl disulphide Mixed aryl-alkyl sulphides anddisulphides methyl phenyl sulphide and disulphide ethyl phenyl sulphideand disulphide amyl phenyl sulphide and disulphide .Certain classes ofthese sulphur compounds may be defined as:

( Disulphides having the general formula: R.-'S-s-R1, wherein R and R1represent substituents selected from the group consisting of alkylgroups or hydrocarbon phenyl groups.

(2)' Organic sulphides having the general for mula R.SR.1, wherein R andR1 represent (a) alkyl groups containing at least 5 carbon atoms each,or (b) phenyl groups or akyl groups containing from 5 to 6 carbon atomseach. I

The alkyl derivatives of the aryl disulphides (e. g., di-xylyldisulphide) and the aryl derivatives .of alkyl disulphides (e. g.,diphenyl diethyl disulphide) are particularly desirable not only becauseof their effectiveness but also because of their ready solubility inmineral oils.

vania oils in the case of mineral oils.

From the point of view of solubility, the most advantageous conditionswould generally result from the use of a compound which is liquid andmiscible with the oil-base used. An example of such compound is diphenylsulphide.

While mineral oil generally is the principal ingredient of thelubricant, it isnot essential that it be the only ingredient other thanthe addition agent, provided that there be no additional ingredientwhich is incompatible with such addition agent. It is within thecontemplation of this invention to include, if necessary or desirable,such other addition agents as are commonlyadded to improve the viscosityindex or cold test of thelubricant and a lubricating compositionaccording to this invention which also has a separate oilinessincreasing agent has been found to be especially effective.

While the lubricating compositions which have been described herein asillustrating one embodiment of the invention have been generallyreferred to as oils, i. e., liquids, this invention is, however, alsoespecially applicable tothe solid and semi-solid types of lubricantscommonly referred to in the trade as greases, bodied oils, etc., andwhich may contain soaps such as sodium, calcium, lead and aluminumnaphthenates, stearates and oleates.

It should be noted that the addition agents of this invention arerelatively chemically stable and will therefore have no corrosive actionupon the metal surfaces with which the lubricant comes in contact.

Other modes of applying the principle of my invention may be .employedinstead of the one explained, change being made as regards thecomposition and method herein disclosed, provided the ingredients orsteps stated by any of the following claims or the equivalent of suchstated ingredients or steps be employed.

I therefore particularly point out and distinctly claim as my invention:

L'An improved lubricating composition comprising a major'proportionofmineral lubricating oil the film strength of which is increased by theinclusion therein of a liquid, oil-miscible organic sulphur compoundselected-from the class consisting of the organic sulphides and organicdisulphides. ,y 2. An improved lubricating composition comprising -amajor proportion of mineral lubricating oil the film strength of whichis increased by the inclusion therein of a liquid, oil-miscible organicsulphur compound selected from the class consisting of the arylsulphides and aryl disulphides. I 3. An improved lubricating compositioncomprising a major proportion of mineral lubricating oil the filmstrength of which is increased by the inclusion thereinof. a liquid,oil-miscible organic sulphur compound selected from the class consistingof the aryl sulphides.

organic sulphides and disulphides.

5. An improved lubricating composition com prising a major proportion.of mineral lubricating oil, the film strength of which has beenincreased by the inclusion therein of a minor amount of a liquid,oil-miscible organic sulphurcompound selected from the class consistingof organic sulphides and disulphides of the type in which the sulphur isattached to a benzenoid ring structure.

